RE: [PATCH v6 8/8] iommu/vt-d: Disallow read-only mappings to nest parent domain

[Liu, Yi L]

> From: Baolu Lu <baolu.lu@xxxxxxxxxxxxxxx>
> Sent: Monday, October 23, 2023 8:18 PM
> 
> On 2023/10/23 19:15, Liu, Yi L wrote:
> >> I would also prefer to introduce is_nested_parent_domain to the user
> >> domain allocation patch (patch 7/8). This field should be checked when
> >> allocating a nested user domain.
> > A ctually, no need. This should be a common check, so iommufd core already
> > has the check. So the parent should be a nest parent domain, otherwise already
> > returned in iommufd.
> >
> > +	if (!parent->nest_parent)
> > +		return ERR_PTR(-EINVAL);
> 
> I know this will not cause errors in the code. But since you are
> introducing is_parent property in the vt-d driver. The integrity of the
> property should be ensured. In this way, it will make the code more
> readable and maintainable.

Ok, if consider it as a property, then it's fine. At first, I just want to
make it as a special flag for this errata. But we cannot predict if there
will be more nested parent special stuffs, then this flag is also needed.

Regards,
Yi Liu